Police say a grenade explosion has wounded at least 24 people, including government personnel, who were responding to a fire in a school campus in the southern Philippines.

Police Inspector Rolly Oranza says firemen, police and government disaster-response personnel were battling the fire in a bunkhouse of security guards inside the state-run Cotabato Foundation College of Science and Technology late Sunday in Arakan town when somebody lobbed a grenade near a firetruck. The attacker escaped.

Oranza said Monday that a policeman, government firefighters, students and school guards were among those wounded with shrapnel and flying debris and were taken to hospitals.

He says investigators have not identified the attacker and were trying to determine if the fire was deliberately started to lure authorities before the blast.